Contact-injected Space Charge in Pet

Absorption current (step-voltage response) measurements complemented by electron-beam and thermally stimulated depolarization experiments on Melinex PET films under stresses of the order 100 MV/m are summarized. They provide clear evidence of field and temperature dependent injection of electronic carriers from metal contacts, leading to the formation of stored space charge. Al, Zn, Sb and In inject predominantly electrons but also, albeit weakly, holes. Au injects only weakly and only holes. The range of electrons trapped beneath an Al cathode is found to be ¿ 1 ¿m at room temperature and 100 MV/m. The results confirm the conclusions drawn by previous authors, that any quasi-steady conduction observed in Melinex PET at high fields is likely to be contact-induced.